The ABD system enables starting or accelerating on smooth and slippery ground. The slipping wheel is braked in order to increase the torque transmitted to the wheel whose tire has traction. During the adjustment process, the engine power should be increased slightly by pressing the accelerator pedal. The ABD system operates at speeds not exceeding 40 km/h. The activation of the ABD system is indicated by the rapid flashing of the ABD system indicator light on the instrument panel.
At speeds above 40 km/h, the drive wheel slips (for example, in icy conditions) indicated by flashing signal lamp. When the key in the steering wheel lock is turned to position 2, the ABD system indicator light on the instrument panel lights up to check the functionality. It goes out after about 2 seconds.
(Article borrowed from the web portal: MERCEDESMAN)